The TOPEX/POSEIDON satellite is and the Jason-1 satellite
soon will be using all the equipment you just read about to measure and understand
the complex and ever-changing topography of the ocean. Knowing the topography
of the ocean and how it is changing enables (helps) meteorologists to predict
the weather better and oceanographers to understand the way the ocean works
and why. This helps fishers to fish better and boats to sail better. Even
the Coast Guard uses this information. They use it to find boats and planes
on the ocean floor (these, of course are boats and planes that have sunk!).

Understanding the topography of the ocean means understanding
the shape of the surface of the ocean--the hills and valleys. It also means
understanding the way heat flows in the ocean. The ocean holds most of the
heat in the Earth's hydrosphere.
The heat in the top three meters of the ocean is equal to the amount of heat
stored in the whole atmosphere. This heat is pushed around by wind and the
ocean currents. It affects the weather and climate considerably. It has always
been a challenge to oceanographers to figure out how these currents move and
how they affect the weather. These currents can be figured out by studying
the topography of the ocean, which is the height of the ocean surface compared
to the Earth's geoid
(click on the "Satellite Altimetry" link to your left to see a picture
of the geoid).

Scientists standing next to Jason-1 give you a good idea of just how big this satellite is.

We've only scanned the top layer here you might say, but
if you wish to examine Jason-1 and space oceanography more closely, here are
some topics to look up: altimeter, radiometer, radiowaves, electromagnetic
radiation, CNES/AVISO, NASA/JPL, surface geostrophic currents,
equi-geopotential surfaces, topography.

Questions that come to mind are:

1. Why is there a particular velocity needed to escape the
pull of gravity?

2. How exactly does a radiometer work? How about an altimeter?

3. How does the Earth's atmosphere affect the readings
of the instruments on Jason?

4. What other factors must be taken into account that would
alter Jason's data readings?

5. How have TOPEX/POSEIDON or Jason-1 affected your life
today?

Critical Thinking Questions:

6. What other things could the information received from
Jason-1 be used for?

7. What other kinds of data could Jason-1 collect?

To find out the answers to these and other
questions you may have, check out our "Helpful
Links"!